121809861 has 12 divisors (see below), whose sum is σ = 176162688. Its totient is φ = 81107304.

The previous prime is 121809859. The next prime is 121809899. The reversal of 121809861 is 168908121.

It is not a de Polignac number, because 121809861 - 2¹ = 121809859 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121809461) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 75 + ... + 15608.

It is an arithmetic number, because the mean of its divisors is an integer number (14680224).

Almost surely, 2^121809861 is an apocalyptic number.

It is an amenable number.

121809861 is a deficient number, since it is larger than the sum of its proper divisors (54352827).

121809861 is a wasteful number, since it uses less digits than its factorization.

121809861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16552 (or 16549 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 36.

The square root of 121809861 is about 11036.7504728521. The cubic root of 121809861 is about 495.7097745526.

The spelling of 121809861 in words is "one hundred twenty-one million, eight hundred nine thousand, eight hundred sixty-one".